ID Pistons...

[docrodg]

OK... so PO had motor rebuilt by motormeister. 1968 911 S motor, I am currently rebuilding it right, but think that the pistons may be wrong type. All are marked 80P26E and Mahle aftermarket lists this correct for 68 but numerous threads here and at pelican state that this is 69 only. So questions are:

Are these correct for 68 911S?
What difference between 68 and 69 S Pistons?

Attachment 82742

[tom1394racing]

Those look like the 67-68S pistons and should be marked 80P25E

[ajwans]

Are you sure Tom, the Mahle website has it listed as 80P26:

Attachment 82772

andy

[docrodg]

Those look like the 67-68S pistons and should be marked 80P25E

They are marked 80P26E... here is photo.
Attachment 82773

Thus the confusion...

[Allen Henderson]

2.0S for 1969. These are higher compression (good!) than the 67 and 68 ones. See below.

-Allen-

[kenikh]

Yep, they sure look like '69S pistons.

*EDIT: Woops - my visual scale is off, as my '69S motor had '67S pistons in it.

[Allen Henderson]

Yep, they sure look like '69S pistons.

Your not painting because

-Allen-

[ajwans]

Now I am confused, take a look at these pictures, sourced from
http://forums.pelicanparts.com/porsc...s-pistons.html

Attachment 82775
Attachment 82776
Attachment 82777

Now I was under the impression that 69S pistons were (as
pictured) similar to 906 pistons which is why they received
the further compression bump over 67-68 S pistons.

The numbers would be the same since they were forged
and then milled to whatever spec Porsche had ordered.

andy

[ajwans]

Here's a thread where a few of us already discussed this topic:

http://www.early911sregistry.org/for...ad.php?t=26875

I have a set of 80.5mm 67S (0.020" oversized) pistons here on my desk (no
camera so you'll just have to trust me) and the number is definitely 80P26E.

andy

[docrodg]

Well, Now even more confused. DO not wnat to go too high on CR as this car is for driving on the road.

Valve pockets are 45mm and 40 mm if that helps...